django 前端模板继承显示model中使用choices的字段

class Need(models.Model):
    """
    任务
    """
    party_a=models.IntegerField(default=0,verbose_name='委托人')
    
    level=models.CharField(max_length=4,verbose_name='任务级别',choices=(('0','d'),
                                                                    ('1','c'),
                                                                    ('2','b'),
                                                                    ('3','a'),
                                                                    ('4','S'),
                                                                    ('5','SS'),
                                                                    ('6','SSS')),default='0')
    
    stag=models.CharField(max_length=4,verbose_name='任务阶段',choices=(('0','待领取'),
                                                                    ('1','被领取'),
                                                                    ('2','测试满意'),
                                                                    ('3','完成任务')),default='0')
    add_time = models.DateTimeField(default=datetime.now, verbose_name='添加时间')

    class Meta:
        verbose_name = '任务'
        verbose_name_plural = verbose_name

    def __str__(self):
        return self.name

<td class="hidden-480 center">{{ need.level }}</td>
<!--……-->                   
<td class="hidden-480 center">{{ need.get_stag_display }}</td>